I am looking through the documentation on Recipes and I find step_string2factor and step_num2factor but I can find no equivalent step_logical2factor. I'm building a classification model and need to convert my T/F outcome to a factor. Does that have to be done in a preprocessing step? If so, why (isn't the point of recipes to provide preprocessing functionality?)?
You can make step_num2factor() work by using step_mutate() with as.numeric.
library(recipes)
library(dplyr)
mtcars0 <- mtcars %>%
mutate(across(c(vs, am), as.logical))
recipe(~., data = mtcars0) %>%
step_mutate(across(c(vs, am), as.numeric)) %>%
step_num2factor(vs, am, transform = function(x) x + 1, levels = c("FALSE", "TRUE")) %>%
prep() %>%
bake(new_data = NULL)
#> # A tibble: 32 × 11
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <dbl>
#> 1 21 6 160 110 3.9 2.62 16.5 FALSE TRUE 4 4
#> 2 21 6 160 110 3.9 2.88 17.0 FALSE TRUE 4 4
#> 3 22.8 4 108 93 3.85 2.32 18.6 TRUE TRUE 4 1
#> 4 21.4 6 258 110 3.08 3.22 19.4 TRUE FALSE 3 1
#> 5 18.7 8 360 175 3.15 3.44 17.0 FALSE FALSE 3 2
#> 6 18.1 6 225 105 2.76 3.46 20.2 TRUE FALSE 3 1
#> 7 14.3 8 360 245 3.21 3.57 15.8 FALSE FALSE 3 4
#> 8 24.4 4 147. 62 3.69 3.19 20 TRUE FALSE 4 2
#> 9 22.8 4 141. 95 3.92 3.15 22.9 TRUE FALSE 4 2
#> 10 19.2 6 168. 123 3.92 3.44 18.3 TRUE FALSE 4 4
#> # … with 22 more rows
The feature you are suggesting has been requested before but has not been implemented yet at the time of this answer.